How to scroll WPF ScrollViewer's content to specific location

Question

I am writing my custom WPF ItemsControl to display a list of item. The items are shown embedded inside a ScrollViewer:

<Style TargetType="MyCustomItemsControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="MyCustomItemsControl">
                    <ScrollViewer x:Name="PART_MyScrollViewer" >
                           <ItemsPresenter/>
                    </ScrollViewer>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
</Style>

I want to make sure that when I move the mouse into the control, a particular item (marked as selected) will be scrolled into the mouse position. In my OnMouseEnter method I am able to find the item but I don't know what to do next. Does anyone have any idea?

protected override void OnMouseEnter(MouseEventArgs e)
{
    for (int i = 0; i < Items.Count; i++)
    {
        ContentPresenter uiElement = (ContentPresenter)ItemContainerGenerator.ContainerFromIndex(i);
        var item = uiElement.Content as MyCustomObject;
        if (item.IsSelected)
        {
            // How to scroll the uiElement to the mouse position?
            break;
        }
    }
}

Solution 1

Something like the following:

var sv = (ScrollViewer)Template.FindName("PART_MyScrollViewer", this); // If you do not already have a reference to it somewhere.
var ip = (ItemsPresenter)sv.Content;
var point = item.TranslatePoint(new Point() - (Vector)e.GetPosition(sv), ip);
sv.ScrollToVerticalOffset(point.Y + (item.ActualHeight / 2));

Solution 2

// How to scroll the uiElement to the mouse position?
uiElement.BringIntoView();

REF: https://msdn.microsoft.com/en-us/library/ms598110.aspx

UPDATE: (thanks to @jmbpiano) Note, it does not bring the control exactly to the current mouse cursor position. It just brings the control to a visible position, where the Operator will be able to click it with the mouse (which in 99% of cases is all someone who finds this question is likely to need).

Solution 3

Use UIElement.TranslatePoint() to calculate what position you want to scroll to

Use ScrollViewer.ScrollToVerticalOffset() to do the scrolling

Comments

[Kay Lee]

Thank you so much ! I spent a whole day with other ways but finally your solution saved me..really really appreciate so much !!!

[jmbpiano]

This doesn't actually do what the asker requested, as it completely ignores the mouse's position, but it does at least bring the control into view on the screen (which in 99% of cases is all someone who finds this question is likely to need). So it's certainly a valuable contribution.

[Nagendra Velaga]

This will help you to scroll the scrollbar with the help of visual tree in wpf/MVVM

[eran otzap]

where did the 'e' arg come from ?

[H.B.]

@eranotzap: From the MouseEnter event handler (see question: OnMouseEnter(MouseEventArgs e)).

[Mike97]

Thanks! This really save the day!